Casting metal tubing



L. CAMMEN.

CASTING METAL TUBING.

APPLICATION FILED JAN.24, 1921.

Patented Apr.

2&5, 1921.

INVENTOR [60/7 Q0717? 6 BY UNITED STATES LEON-CAMMEN, OF NEW YORK, N. Y.

oas'rme METAL TUBING.

Application filed January 24, 1921.

'To all whom it may concern ,Be it knownthat I, LEON CAMMEN, a citizen of the United States, and resident of borough of Manhattan, in the city, county, and State of New York, have invented certain new and useful Improvements in Casting Metal Tubing, of which the following is a specification.

This invention refers to the production by centrifugal casting of tubing from metals.

having a high melting point and such that overheating previous to castin is not desirable. Such is for example onel metal which has a melting point 1n the proximity of 2500 deg. F., and which loses some of its copper content if heated considerably beyond its melting point.

on such metal is cast centrifugally by the usual processes (melting the metal in a crucible and pourin it into a cold mold), it'chills long before 1t has had time to form a pipe, which is the reason why no Monel metal tubing has been hitherto produced.

The present invention describes a method of procedure by which the above difficulties are successfully overcome.

In the illustrations,

Figure 1 is a cross-section of the mold normal to the axis of spinning;

Fig. 2 is a view from on-top of part of the mold along a section along the axis of rotation;

Fig. 3 is a sectional view of the same mold, including a metal rod from which a tube is to be made.

Essentially, the present invention involves the use of a mold of such construction that the part which comes in contact with the metal, could be heated to such a temperature that the metal would remain fluid when coming into contact with it, and yet the entire mold would remain sufiiciently strong mechanically to be used for centrifugal spinning.

Assuming that it is desired to make tubing of such material as Monel metal, this latter has to be poured into the mold at a tem perature which cannot be lower than say.

2480 de F. (theoretical melting temperature of ilonel metal), and not higher than say 2600 deg. F., as experience has shown that above that temperature the Monel metal begins to lose its cop er.

is obvious there ore that the lining of the mold into which the metal is poured, must have a temperature in the region of Specification of Letters Patent.

Patented Apr. 26, 1921.

Serial No. 439,574.

2000 deg. F. (white heat for graphite), in order to permit the metal to stay hot long enough to complete the process of spinning.

These figures are based on the general experience in founding Monel metal, and on my own tests.

On the other hand, however, Monel metal tubing has to be cast in lengths of 12 to 20 feet, and diameters varying from *3 inch up. It is obvious to any person who has had experience in foundry work that it is impossible to heat a linin 12 to 20 ft. long, and of a small inside diameter, by shooting a flame, such as a gas flame, through it, as onlythe ends will be heated in this manner. The other, and simpler, way. viz., to heat the pipe together with the lining to a white heat, is entirely out of the question, as steel pipe heated to white heat would be so weak mechanically that the lining would buckle and crack as soon as the spinning started.

To obviate these difiiculties, the present invention provides a process of casting by centrifugal spinning in which use is made of a composite mold, such as is shown in Fig. 1, and the lining is heated electrically. In Fig. 1, 1 is a conducting (electrically) lining, such as graphite; 2 is a body acting as an electrical insulator, thus confining the flow of current to the lining 1, and keeping it away from the metal pipe 3, and finally this latter pipe 3, the purpose. of which is to give mechanical strength to the mold.

The current may be introduced into the lining 1, as shown in Fig. 2, by heavy copper or steel rings l and 5 (which may be water cooled in the usual manner if desired), connected by leads 6 and 7 with a source of electric current, such as the secondary of a transformer-8 (prima not shown).

The intermediary bd dy 2 should be preferably selected in such a manner as to be a poor conductor both electrically and thermally, under which conditions the lining 1 may be brought to a white heat, while the metal pipe 3 remains comparatively cool.

Fig. 3 shows one more step in the application of the same principle. The graphite lining 1 is closed by carbon blocks 11 and 10 insulated from the pipe 3 b the intermediary body 2, and a rod 12 o the metal from which the pipe is to be made is held between the end blocks 9 and 10, current being supplied to these latter by the leads 6 and 7 in the same manner as in Fig. 2.

As the conductivity of the metal rod is very much superior to that of the graphite lining, the main current will go through the rod. Enough current however will go through the lining to make it hot, which is also assisted by the radiation from the rod. In order to keep the lining uniformly hot, it is advisable to rotate the mold slightly, as by pulley 13, and belt (not shown) during the process of melting of the rod, which is especially advisable toward the end of the process of melting when the rod sags, and if stationary, is apt to overheat one section of the lining, and cause subsequent cracking. v

No claims are made for the mold itself, as this will form the subject of a separate application.

claim:

1. A process of manufacture of metal tubing by centrifugal casting, wherein is used a composite mold, consisting of not less than three parts, such that part one which comes in contact with the metal of the tube, is electro-conductive; part two,

essentially surrounding part one, is electroinsulative, and part three is of metal; and wherein further the lining, which is part one of the mold, is heated, previous to the pouring of the metal, by an electric current to a temperature close to the melting point of the metal.

2. A process of manufacture of metal tubing by centrifugal casting wherein is used a composite mold consisting of not less than three parts, such that part one which comes in contact with the metal of the-tube is electro-conductive; part two essentially surroundin part one, is electro-insulative, and part t ree is of metal; and wherein further the metal of the tube is heated to the melting point by the passage of the electric current previous to the start of centrifugal spinning.

3. A process of manufacture of metal tubing by centrifugal casting wherein is used a composite mold consisting of notless than three parts, such that part one which the melting point by the passage of anelecv tric current previous to the start of the centrifugal spinning, but during the heating of the metal of the tube the mold is subjected to a rotation at a speed below that used for centrifugal spinning.

4. A process of manufacture of metal tubing by centrifugal casting wherein the metal of the tube is heated to the melting point by the passage of an electric current in the same mold in which it is subjected to the spinning process.

5. A process of manufacture of metal tubing by centrifugal casting wherein the metal of the tube is heated to the melting point by the passage of an electric current in the same mold in which it is subjected to the spinningprocess, the mold, during the heating of the metal. being rotated at a speed below that used for centrifugal sping- S1gned at New York, in the county and State of New York, this 19 day of January,

LEON CAMMEN. Witness:

C. C. CAMMEN. 

